Isolated H‐bridge DC–DC converter integrated transformerless DVR for power quality improvement

This study presents a new H‐bridge DC‐DC converter‐based transformerless dynamic voltage restorer topology (DVR). The proposed system can compensate balanced and unbalanced voltage sag/swell that are the most common electrical power quality problems and offers advantages over conventional DVR topologies by providing the isolation with high‐frequency transformer (HFT) rather than bulky injection transformers and by employing shunt converter to eliminate the requirement of an energy storage unit. The system is composed of H‐bridge DC–DC converter equipped with a HFT with one primary and three secondary windings and transformerless DVR. The single‐phase shift modulation method is used for each series converter independently to provide the bidirectional power flow control of DC–DC converter, whereas in‐phase compensation method with a hybrid detection algorithm is used to mitigate voltage sag/swell. An LC filter is employed to attenuate the switching ripple harmonics on the output of the DVR. The performance of the proposed system is verified experimentally on a three‐phase, three‐wire, 380 V, 10 kVA prototype.